Reset mechanisms

ABSTRACT

A reset mechanism for a stop-watch is operable to rotate two cams on the staves of the minute and second hands respectively of the watch, back into datum angular positions. Depression of a reset button of the mechanism actuates an operating lever that engages with a cam surface of a pivotally-mounted support-member to pivot the support member towards the cams against the action of a spring. A striker of unitary construction and having camming surfaces for engaging the cams is pivotally mounted on the support member but is restrained from more than small angular displacement relative to the support member by a pin which from the striker member engages in an oversized hole in the support member. Pivoting of the support-member carries the striker to bring its two camming-surfaces into engagement with the two cams respectively, the loose mounting of the striker on the support member permitting it limited adjustment of orientation relative to the support-member to ensure that the camming surfaces are both brought into positive engagement with their respective cams. The striker is constrained to movement along a path which is defined by a slot in the base plate of the mechanism and which is spaced from the support-member pivot, the slot being engaged by a pin which is carried on the striker and which is spaced from the pivot of the striker with the support member.

United States Patent 1191 Boult RESET MECHANISMS Swansea,Glamorganshire, Wales Primary ExaminerGeorge H. Miller, Jr. Attorney,Agent, or Firm+George Vande Sande 1451 Mar. 12, 1974 [57] ABSTRACT Areset mechanism for a stop-watch is operable to ro tate two cams on thestaves of the minute and second hands respectively of the watch, backinto datum angular positions. Depression of a reset button of themechanism actuates an operating lever that engages with a cam surface ofa pivotally-mounted supportmember to pivot the support member towardsthe cams against the action of a spring. A striker of unitaryconstruction and having camming surfaces for engaging the cams ispivotally mounted on the support member but is restrained from more thansmall angular displacement relative to the support member by a pin whichfrom the striker member engages in an oversized hole in the supportmember. Pivoting of the support-member carries the striker to bring itstwo camming-surfaces into engagement with .the two cams respectively,the loose mounting of the striker on the support member permitting itlimited adjustment of orientation relative to the support-member toensure that the camming surfaces are both brought into positiveengagement with their respective cams. The striker is constrained tomovement along a path which is defined by a slot in the base plate ofthe mechanism and which is spaced from the support-member pivot, theslot being engaged by a pin which is carried on the striker and which isspaced from the pivot of the striker with the support member.

7 Claims, 2 Drawing Figures PATENTEDMAR 12 1514 3.7961341 SHEET 1' [1F 2RESET MECHANISMS This invention relates to reset mechanisms and isparticularly, although not exclusively, concerned with the provision ofsuch mechanisms for resetting the hands of a stop-watch to zero.

One form of reset mechanism in common use at present provides acam-piece which when released is operable under the influence of aspring to cooperate with cams mounted on the staves of the hands of thewatch to return those hands to a datum position.

Practical difficulties arise in using the above form of reset mechanismnot the least of which lies in the use of a spring to effect theresetting operation. Again, in view of the accuracy with which it isdesired to reset the hands of a stop watch to zero, the various parts ofthe reset mechanisms used heretofore have had to be formed, and thentheir assembly carried out, with a great accuracy. This has theinevitable effect of increasing both the cost of the various parts ofthe watch and the costs of assembling those parts in a watch.

According to this invention a reset mechanism comprises a striker memberwhich is loosely mounted on a movably-mounted support member and whichhas a camming surface for engaging a reset cam of the mechanism forresetting the cam to a datum position, and operating means which isactuable to engage with the support member and to cause it to move suchthat the camming surface of the strikermember engages the reset cam toreset it to its datum position.

One advantage of the invention over the prior proposals is that thevarious parts of the reset mechanism may be manufactured to a lesser (orat least the same) degree of accuracy than has heretofore beennecessary. Another advantage resulting from the same feature of theinvention is that the loose coupling between striker and support memberspermits their assembly very cheaply and quickly.

Further advantages including, for example, the nonreliance on a springto effect the resetting action, will become apparent from thedescription of a stop-watch including the reset mechanism which follows.

The stop-watch is described, by way of example only, with reference tothe accompanying drawings, which show in FIGS. 1 and 2 respectively thewatch before and after resetting of the hands.

Referring to FIGS. 1 and 2, the casing 9 of the watch carries a movementof which only one mounting plate 10 is shown. A winder-reset button 12is carried by the movement and extends through a hole in the casing 9.Also mounted on the movement to extend through a hole in the casing 9 isa stop-start button 13. The button 13 may operate as described in mycopending U. 5. Pat. application Ser. No. 279,400, filed Aug. 10, 1972,in starting and stopping operation of the watch. The reset button 12includes a knurled winder knob 14 and stem 15. The stem 15 connects tothe movement of the watch and may be operated to wind-up the mainspringof the watch in any well known way. Whenever the button is depressed aflange 17, which is formed integrally with the stem 15 engages a boss 18formed of an operating lever 19 pivotally mounted at one end, 20, on theplate 10. The operating lever 19 carries a shouldered stud 21 located ina slot 22 formed in the mounting plate 10. The mounting plate 10 alsocarries an arcuate support member 23 pivotally mounted at one end 24.

The striker member 28 is constrained to follow a predetermined pathrelative to the mounting plate 10 during movement of the support member23. This path is defined by a slot 30 in the plate 10, and is followedby a pin member 29 that is carried by the striker member 28 to engagewith the slot 30. The other end of member 23 is formed with a cammingsurface 26 and pivotally supports, at 27, a striker member 28. Thestriker 28 is formed with two camming surfaces 31 and 32 which areengageable respectively with two reset earns 33 and 34. The cams 33 and34 are rigidly mounted on the staves carrying the minute and secondhands of the watch. A pin or half-sheered dowel in striker 28 engagesloosely in a hole 35 in the arcuate support member 23 so that striker 28is free to rotate through a small angle about its pivotal support 27. Aspring 36 is provided to bias the arcuate support member away fromthecams 33 and 34 as shown.

Operation of the mechanism will be described assuming that the mechanismis initially in the position shown in FIG. 1 that is to say with thehands stopped but not reset. Depression of the button 12 to reset thehands of the watch to zero, causes the flange 17 on the winding stem 15to move inwardly hard against the boss 18. Continued depression ofbutton 12 moves the operating arm 19 about its pivot 20 until the freeend of arm 19 engages the surface 26 of the arcuate support member 23.Member 23 is forced inwardly carrying with it the striker member 28 tofollow the path defined in the mounting plate 10 by the slot 30, untilthe surfaces 31 and 32 engage the earns 33 and 34 respectively. Furthermovement of button 12 results in the earns 33 and 34 being reset to theposition shown in FIG. 2. When released the button 12 is driven back tothe position shown in FIG. 1 under the influence of spring 36.

The floating feature of striker 28 provided by the loose mounting of thestriker 28 on the support member 23, and acting within the constraintimposed by engagement of the pin 29 in the slot 30, ensures that cams 33and 34 are returned to zero accurately and variations in manufacturingaccuracies and finish are compensated for; The surfaces 31 and 32 andthe faces of the cams 33 and 34 which they engage may be flat, as shown,or curved. In this latter respect the faces 31 and 32 are preferablyconvex and the faces on the .camsshaped to conform with them. The camshaping facilitates return of each cam to its zero, datum positionthrough the shortest available angular path when acted upon by thestriker 28.

Means may be provided, associated with the stopstart mechanism forpreventing operation of the reset mechanism while the hands of the watchare in motion.

I claim: l. A reset mechanism comprising a base member, a

reset cam which is mounted on the said base member for angular movementinto a datum angular position with respect to said base member, asupport member, pivot means pivotally mounting said support member onsaid base member for movement relative to said cam, a striker member,further mounting means loosely mounting said striker member on thesupport member,

datum angular position, and means interconnecting said striker memberand said base member to constrain the said striker member to follow apredetermined path relative to the said base member, and thereby to saidcam, during said movement of the support member, said interconnectingmeans being operative along said path to interconnect a part of thestriker member spaced from the said further mounting means with a partof the said base member spaced from said pivot means.

2. A reset mechanism as claimed in claim 1 in which the support memberhas a cam-surface part, and the said operating meanscomprises apivotally mounted lever member having a camming surface for engagingsaid cam-surface part of the support member to effect the said movementof the support member.

3. A reset mechanism according to claim 1 in which said meansinterconnecting said striker and base members comprises a pin elementcarried by one of said striker and base members to engage in a slot inthe other of the said striker and base members.

4. A reset mechanism as claimed in claim 1 in which said furthermounting means comprises means pivotally mounting the striker member onthe support member, and means to restrain said striker member fromsubstantial pivotal movement relative to the support member when thestriker member is brought into said engagement with said cam.

5. A reset mechanism according to claim 4 in which said means torestrain said striker member comprises a pin element carried by one ofthe siad striker and support members to engage in an aperture in theother of said striker and support members.

6. In a stop-watch, a reset mechanism comprising a base plate, a resetcam mounted on the staff of a hand of the stop-watch and movableangularly to a datum angular position with respect to the base plate toreset the said hand of the stop watch, a support member, pivot meanspivotally mounting said support member on said base plate for movementrelative to said base plate and said cam, a striker member, furthermounting means loosely mounting said striker member on the supportmember, .the striker member having a camming surface for effectingengagement with the said cam to displace said cam angularly into saiddatum angular position,

operating means actuable to engage with the support member to move it tobring the said striker member into said engagement with the cam so as toreset the cam to its said datum angular position, and meansinterconnecting said striker member and the said base plate to constrainthe said striker member to follow a predetermined path relative to thesaid base plate, and thereby to said cam, during said movement of thesupport member, said base plate having a slot therein that is spacedfrom said pivot means to define said path, and said interconnectingmeans comprising an element carried by said striker member to engage insaid slot throughout said movement of the support member, said elementbeing spaced on said striker member from the said further mountingmeans.

7. In a stop-watch, a reset mechanism comprising: a base member; a pairof reset cams mounted respectively on the staves of the minute andsecond hands of the watch, said cams being movable angularly withrespect to said base member into respective datum angular positions toreset the hands of the stop watch; a support member; mounting meanspivotally mounting said support member on said base member for movementrelative to the said pair of cams; a unitary striker member looselymounted on the support member, the striker member comprising two cammingsurfaces each for effective engagement with a respective one of saidpair of reset cams, and means rigidly interconnecting the two cammingsurfaces with one another as a unitary whole; operating means actuab'leto engage with the support member to move it to bring the said strikermember into said engagement with the said pair of reset cams so as toreset the said pair of cams to their respective datum positions;and'means interconnecting the striker member with the base member toconstrain the striker member to follow a predetermined path relative tothe said base member, and thereby to said cams, during the said movementof the support member said base member having a slot therein that isspaced from said mounting means to define said path, and saidinterconnection means comprising an element carried by said strikermember to engage in said slot throughout said movement of the supportmember.

1. A reset mechanism comPrising a base member, a reset cam which ismounted on the said base member for angular movement into a datumangular position with respect to said base member, a support member,pivot means pivotally mounting said support member on said base memberfor movement relative to said cam, a striker member, further mountingmeans loosely mounting said striker member on the support member, thestriker member having a camming surface for effecting engagement withthe said cam to displace the cam angularly into said datum angularposition, operating means actuable to engage the support member to moveit to bring said striker member into said engagement with the cam so asto reset the cam to its said datum angular position, and meansinterconnecting said striker member and said base member to constrainthe said striker member to follow a predetermined path relative to thesaid base member, and thereby to said cam, during said movement of thesupport member, said interconnecting means being operative along saidpath to interconnect a part of the striker member spaced from the saidfurther mounting means with a part of the said base member spaced fromsaid pivot means.
 2. A reset mechanism as claimed in claim 1 in whichthe support member has a cam-surface part, and the said operating meanscomprises a pivotally mounted lever member having a camming surface forengaging said cam-surface part of the support member to effect the saidmovement of the support member.
 3. A reset mechanism according to claim1 in which said means interconnecting said striker and base memberscomprises a pin element carried by one of said striker and base membersto engage in a slot in the other of the said striker and base members.4. A reset mechanism as claimed in claim 1 in which said furthermounting means comprises means pivotally mounting the striker member onthe support member, and means to restrain said striker member fromsubstantial pivotal movement relative to the support member when thestriker member is brought into said engagement with said cam.
 5. A resetmechanism according to claim 4 in which said means to restrain saidstriker member comprises a pin element carried by one of the siadstriker and support members to engage in an aperture in the other ofsaid striker and support members.
 6. In a stop-watch, a reset mechanismcomprising a base plate, a reset cam mounted on the staff of a hand ofthe stop-watch and movable angularly to a datum angular position withrespect to the base plate to reset the said hand of the stop watch, asupport member, pivot means pivotally mounting said support member onsaid base plate for movement relative to said base plate and said cam, astriker member, further mounting means loosely mounting said strikermember on the support member, the striker member having a cammingsurface for effecting engagement with the said cam to displace said camangularly into said datum angular position, operating means actuable toengage with the support member to move it to bring the said strikermember into said engagement with the cam so as to reset the cam to itssaid datum angular position, and means interconnecting said strikermember and the said base plate to constrain the said striker member tofollow a predetermined path relative to the said base plate, and therebyto said cam, during said movement of the support member, said base platehaving a slot therein that is spaced from said pivot means to definesaid path, and said interconnecting means comprising an element carriedby said striker member to engage in said slot throughout said movementof the support member, said element being spaced on said striker memberfrom the said further mounting means.
 7. In a stop-watch, a resetmechanism comprising: a base member; a pair of reset cams mountedrespectively on the staves of the minute and second hands of the watch,said cams being movable angularly with respect to said base member intorespective datum angular positions to reset the hands of the stop watCh;a support member; mounting means pivotally mounting said support memberon said base member for movement relative to the said pair of cams; aunitary striker member loosely mounted on the support member, thestriker member comprising two camming surfaces each for effectiveengagement with a respective one of said pair of reset cams, and meansrigidly interconnecting the two camming surfaces with one another as aunitary whole; operating means actuable to engage with the supportmember to move it to bring the said striker member into said engagementwith the said pair of reset cams so as to reset the said pair of cams totheir respective datum positions; and means interconnecting the strikermember with the base member to constrain the striker member to follow apredetermined path relative to the said base member, and thereby to saidcams, during the said movement of the support member said base memberhaving a slot therein that is spaced from said mounting means to definesaid path, and said interconnection means comprising an element carriedby said striker member to engage in said slot throughout said movementof the support member.